Pile Load Tests Research Articles

Discussion of “Validation of Monotonic and Cyclic p-y Framework by Lateral Pile Load Tests in Stiff, Overconsolidated Clay at the Haga Site” by Youhu Zhang, Knut H. Andersen, Philippe Jeanjean, Kjell Karlsrud, and Torgeir Haugen

Discussion of “Validation of Monotonic and Cyclic p-y Framework by Lateral Pile Load Tests in Stiff, Overconsolidated Clay at the Haga Site” by Youhu Zhang, Knut H. Andersen, Philippe Jeanjean, Kjell Karlsrud, and Torgeir Haugen

Closure to “Validation of Monotonic and Cyclic p-y Framework by Lateral Pile Load Tests in Stiff, Overconsolidated Clay at the Haga Site” by Youhu Zhang, Knut H. Andersen, Philippe Jeanjean, Kjell Karlsrud, and Torgeir Haugen

Closure to “Validation of Monotonic and Cyclic p-y Framework by Lateral Pile Load Tests in Stiff, Overconsolidated Clay at the Haga Site” by Youhu Zhang, Knut H. Andersen, Philippe Jeanjean, Kjell Karlsrud, and Torgeir Haugen

Determination of Piles Bearing Capacity using Empirical Methods and (AllPile 6) Software -Cases studies Portsudan and Khartoum Cities

Different methods have been used to determine the pile bearing capacity such as static equations, dynamic equations, empirical methods (EMs), numerical methods, computer software programs, and the pile static load test, these methods were giving different values for pile bearing capacity. In this paper, three empirical methods (Ems) have been selected (Brinch-Hansen, Chin-Kondner, and Decourt) and (AllPile 6) software (AP) has been applied to determine the capacity load of piles for six cases study of drilled concrete piles with a diameter ranging from 800 mm to 1500mm and embedded length ranged 10.5m to 26m. Four of those six piles are located at Portsudan city near the red seacoast and two piles are located in Khartoum city. The results of the pile bearing capacity (PC) calculations obtained using the above-mentioned different methods were compared with results produced by the pile load test. In all six cases study, the settlement of piles was limited, settlement failure was not reached. The results show that the AllPile 6 (AP) and the three mentioned empirical methods (Ems) gave reasonable piles bearing capacity, the (AP) and (BHM) gave the better result than the CKM and DM. While (DM) gave results similar to results determined using the (CKM). However, it was not preferred to use the (CKM) and (DM), unless the failure settlement has occurred in the pile load test.

Assessment of Stress in the Soil Surrounding the Axially Loaded Model Pile by Thin, Flexible Sensors.

Foundation piles transfer the applied vertical load to the surrounding soil by skin friction and base resistance. These two components induce stress in the soil. The load transfer is still not fully recognized, and some pile load tests analyses have raised many doubts. The present paper aimed to measure the stress levels during pile load tests in laboratory conditions. This research examined the possibilities of using thin, flexible sensors in measuring the stress in soil. Two sensors were used: tactile pressure sensor with mapping system and color film pressure sensors with digital analyzing. Calibration and preliminary tests of the sensors have been described. This calibration proved that this kind of sensor could measure the stress in the soil in laboratory conditions. The results of stress distribution in the soil, shown as pressure maps, have been presented. Significant stress changes were observed in pile load tests. Rough and smooth piles were compared in the analyses. Stress distribution was the result of simultaneous interaction of pile skin and base. The knowledge about stresses surrounding the pile allows us to carry out a deeper analysis of the pile–soil interaction.

BACK ANALYSIS OF OSTERBERG-CELL PILE LOAD TEST BY MEANS OF THREE-DIMENSIONAL GEOTECHNICAL MODELING

In 3D geotechnical modelling it is essential for the realistic simulation of soil behavior that the parameters of the hardening soil with small strain constitutive model are specified appropriately. The possibility of deriving these parameters for very stiff cohesive soils similar to the so called Kiscell clay that has a significant role in deep construction projects in Budapest, from laboratory and field tests is rather limited. The results of the pile load test completed for the MOL Campus high-rise building project proved to be useful data source. The article presents the circumstances of the quoted Osterberg-cell pile load tests and the modelling of the pile performed by the above-mentioned soil model. The parameters specified on the basis of laboratory tests - and in absence of those based on literature - data can be fine-tuned by approaching the load test results.

Use of Shear Wave Velocity for Foundation Design

This paper describes an approach for utilizing in-situ measurements of shear wave velocity Vs to carry out preliminary and check design calculations for shallow and deep foundations. For estimates of foundation movements, Vs can be used directly to estimate the small-strain stiffness of the soil or rock strata, while for ultimate capacity calculations, use is made of empirical correlations between Vs and penetration resistance measures, which in turn are correlated to the foundation resistance characteristics. The approach is applied to a series of published tests on shallow footings, and on a series of pile load tests for a very tall building. For these cases, comparisons of the calculated with the measured load—settlement behaviour indicates that the suggested approach provides a reasonable, albeit somewhat conservative, level of agreement.

FIELD STUDY ON SOFT SOIL IMPROVEMENT USING CONTINUOUS FLIGHT AUGER (CFA) PILES

The continuous flight auger (CFA) piling technique is commonly used where the presence of groundwater or potentially collapsible material reduces the cost-effectiveness of bored piling techniques. Whilst generally considered a soil replacement technique, the process of pumping concrete under pressure during the pile installation can result in a significant improvement of the surrounding soil, particularly in low strength soil conditions. In this study, a case study is analyzed. An oil storage tank was intended to be constructed on soft clay in southern Iraq. The tank has a diameter of 46 m. Cone penetration test, drilling boreholes, and field tests have been conducted in the tank site. A decision was made to improve the mechanical properties of soft clay of the site by CFA piles before construction of the tank. The depth of CFA pile constructed is 16 m, with a diameter of 0.5 m and spacing between piles is 4.2 m. Three types of in-situ tests have been conducted: Conventional plate load test on the soil before and after improvement; large plate load test for soil after improvement; and pile load test on CFA pile. It was concluded that construction of CFA piles shows an increase in the bearing capacity by about 110% for the soil directly around piles and 70% for soil within 2 m from the center of piles. Large plate load test result for the pile with surrounding soil revealed that the ultimate bearing capacity increases to 500 kN/m2. So that the overall loading area showed an increase in the bearing capacity of about 350% when CFA piles are constructed.

Wet and dry installation effects on the capacity of helical piles in loess deposits

ABSTRACT Vast land areas in northeastern Iran are covered with loess soils being susceptible to collapse and excessive settlement after moistening. Different improvement techniques were developed for loess soils, including compaction, immersion, or reinforcement. However, the shortcomings, such as limited improvement depth and lack of control over the treated area restrict these techniques’ effectiveness. The present study suggests the installation and application of helical piles as a combination of improvement techniques. About 13 uniform triple-helix piles of 3 m length, 250 mm blade diameter, and 750 mm blade spacing were installed via two different dry and wet installation methods. Static pile load tests were performed for all the helical piles. The results showed that the pile load tests were highly dependent on the moisture content at the testing time, the crowd force and the injected water pressure. Eventually, wet installed piles led to a more stable structure of loess soils than dry installed piles subjected to water.

The DINGO database of axial pile load tests for the UK: settlement prediction in fine-grained soils

ABSTRACT The availability of reliable field data is critical for the advancement of geotechnical engineering. This is particularly the case for piled foundations; due to the substantial geotechnical uncertainties. The settlement (performance) predictions from established analytical methods may deviate from field measurements by as much as an order of magnitude. This paper provides a statistical assessment of the uncertainty of predictions of pile performance under axial loading using an openly accessible geotechnical database of pile load tests from the United Kingdom. The collected database information was classified by pile type, location, test data quality and availability of geotechnical data. With reference to the data from fine-grained soils, two analytical models were employed to predict foundation settlement. The settlement prediction performance was then studied statistically and the model bias and error compared with reference to the aforementioned categories to identify the impact of different sources of uncertainty and evaluate the use of both models for future geotechnical practice. The two models investigated generally over-predict settlement, which is likely due to conservative selection of key model parameters, such as soil strength.

Optimizing the Arrangement of Strain Gauges in Pile Load Testing

Abstract The use of strain gauges in a deep foundation element static load test is a common technique to obtain soil strata mobilized resistance. The typical arrangement is several gauges at each of several discrete depths. The gauges at each depth are averaged, the average is converted to a force, and the forces at various depths are differentiated to compute force dissipation into the soil. A simple error analysis leads to the optimal arrangement of gauges in the element cross section, accounting for uneven distribution of strain across the cross-section plane of the element and the possibility of gauge malfunction. By using a case history as an example, the optimal vertical spacing of gauge levels is discussed.

Empirical Bearing Capacity Formula for Steel Pipe Prebored and Precast Piles Based on Field Tests

Abstract In this study, analysis of real-scale field pile loading test results on 20 fully instrumented steel pipe test piles will be carried out, to propose a modified empirical formula to estimat...

A Parametric Numerical Study for Diagnosing the Failure of Large Diameter Bored Piles Using Supervised Machine Learning Approach

The full-scale static pile loading test is without question the most reliable methodology for estimating the ultimate capacity of large diameter bored piles (LDBP). However, in most cases, the obtained load-settlement curves from LDBP loading tests tend to increase without reaching the failure point or an asymptote. Loading an LDBP until reaching apparent failure is seldom practical because of the significant amount of settlement usually required for the full shaft and base mobilizations. With that in mind, the supervised learning algorithm requires a huge labeled data set to train the machine properly, which makes it ideal for sensitivity analysis, forecasting, and predictions, among other unsupervised algorithms. However, providing such a huge dataset of LDBP loaded to failure tests might be very complicated. In this paper, a novel practice has been proposed to establish a labeled dataset needed to train supervised machine learning algorithms on accurately predicting the ultimate capacity of an LDBP. A comprehensive numerical parametric study was carried out to investigate the effect of both pile geometrical and soil geotechnical parameters on both the ultimate capacity and settlement of an LDBP. This study was based on field measurements of loaded to failure LDBP tests. Results of the 29 applied models were compared with the calibrated model results, and the variation in LDBP behavior due to change in any of the hyperparameters was discussed. Accordingly, three primary characteristics were identified to diagnose the failure of LDBPs. Those characteristics were utilized to establish a decision tree of a supervised machine learning algorithm that can be used to predict the ultimate capacity of an LDBP.

Pile Load Tests and Foundation of the Highest Skyscraper in Northern Germany

This paper gives a short overview of concept and structural design of the highest skyscraper in northern Germany. The new building will get an overall height of 245 m. Due to the little bearing capacity of the ground a deep foundation is needed. For the foundation piles with length up to 75 m will be executed. In advance, to determine the bearing capacity of the surrounding soil, pile load tests are carried out.

Application of Geodetic Measuring Methods for Reliable Evaluation of Static Load Test Results of Foundation Piles

Geodetic measuring methods are widely used in the course of various geotechnical works. The main purpose is usually related to the location in space, geometrical dimensions, settlements, deflections, and other forms of displacements and their consequences. This study focuses on the application of selected surveying methods in static load tests (SLTs) of foundation piles. Basic aspects of the SLT are presented in the introductory section, together with the explanation of the authors’ motivation behind the novel (but already sufficiently tested) application of remote methods introduced to confirm, through inverse analysis, the load applied to the pile head under testing at every stage of its loading. Materials and methods are described in the second section in order to provide basic information on the test site and principles of the SLT method applied. The case study shows the methodology of displacement control in the particular test, which is described in light of a presented review of geodetic techniques for displacement control, especially terrestrial laser scanning and robotic tacheometry. The geotechnical testing procedure, which is of secondary importance for the current study, is also introduced in order to emphasize the versatility of the proposed method. Special attention is paid to inverse analysis (controlling of the pile loading force on the basis of measured deflections, and static calculations by means of standard structural analysis and the finite element method (FEM)) as a tool to raise the credibility of the obtained SLT results. The present case study from just one SLT, instrumented with various geodetic instrumentation, shows the results of a real-world dimensions test. The obtained variability of the loading force within a range of 15% (depending on real beam stiffness) proves good prospects for the application of the proposed idea in practice. The results are discussed mainly in light of the previous authors’ experience with the application of remote techniques for reliable displacement control. As only a few references could be found (mainly by private communication), both the prospects for new developments using faster and more accurate instruments as well as the need for the validation of these findings on a larger number of SLTs (with a very precise definition of beam stiffness) are underlined in the final remarks.

PERBANDINGAN HASIL UJI KAPASITAS DUKUNG TIANG PANCANG PADA TANAH LEMPUNG JENUH SKALA LABORATORIUM DENGAN PERHITUNGAN ANALISIS STATIS

Pile bearing capacity, is an important parameter in infrastructure design. The pile driving process, especially in saturated clay soils, results in an increase in pore pressure which affects the bearing strength capacity of the pile foundation immediately after erection. By knowing the com-parison of various ways to calculate the bearing capacity of a pile foundation, especially in clay soils, various influencing parameters can be studied and to be taken in determining the bearing ca-pacity of a pile foundation. The test is carried out by comparing the value of the pile bearing capacity of a laboratory scale pile model with the results of the calculation of the pile bearing capacity using the static analysis method based on the results of the test parameters of the soil. The clay soil con-ditions in the test are limited to saturated conditions. The reading of the change in pore water pres-sure is carried out using a pressure transducer during the pile driving process. Based on the pile loading test results in the laboratory, the pile bearing capacity results were 0.31 kN, while the bearing capacity results based on the static analysis method were 0.75 kN. The difference in pile bearing carrying capacity is caused by excess pore water pressure that appears around the ground during the driving process.

Investigation on multi under reamed piles with small bulb diameter in clay

ABSTRACT This paper presents a study conducted on a multi-under-reamed pile having a small bulb size, but more than two in number. The proposed design is aimed to mobilize the side friction along the cylindrical surface formed between the bulbs to a greater extent and thereby enhance the load-carrying capacity with the minimum use of concrete. Pile load test was carried out on full-scale models of the conventional pile, and the proposed multi-tiny bulb pile. Finite-element analyses were performed to analyse the capacity of the proposed pile and to compare it with conventional bored cast-in-situ piles tested in the field. The validated model was then used to study the effect of various parameters on load-deformation behaviour and to understand the deformation contours of Multi-tiny bulb pile and to compare it with other existing pile geometries. It was found that Multi-tiny bulb piles of bulb diameter equal to the shaft diameter of conventional piles mobilize almost the same capacity as that of a solid conventional pile of uniform shaft diameter equal to that of bulb diameter of the former. The volume of material consumed by a Multi-tiny bulb pile to attain this was only 42% of a conventional pile considered for the study. The study suggests that Multi-tiny bulb piles if properly employed in the field with quality control can effectively replace the conventional piles in clayey stratum and also is a cost-effective option in terms of material input.

Installation of Bored Piles with a Protective Silicate Shell of a New Design in Saline Silty-Clayey Soils

Designing advanced methods of corrosion protection and increasing the bearing capacity of pile foundations on saline clayey soils is a priority geotechnical task in Kazakhstan. The formation of a suffusion-resistant waterproof shell was achieved by silicatization of a borehole before concreting, by the installation of a mold into the borehole and the impregnation of a sodium silicate solution into the space between the mold and the soil under pressure. After coagulation of the silicate solution, the mold was removed and the formed shell was filled with corrosion-resistant concrete. Full-scale static pile load tests were conducted in the construction site “Retaining wall on Mount Koktobe” in Almaty. The bearing capacity of the piles with the protective silicate shell exceeded the bearing capacity of an ordinary pile by 2.5 times on average without wetting the site, and 3.2 times after prolonged wetting. The numerical model had a close relationship with the average experimental curve obtained when conducting six static pile load tests with the protective shell. A large economic effect of the developed piling technology with a protective shell was achieved, with a significant reduction in the cost of piling, equal to 27.85%.

The Effect of w/c Ratio of Compacted Bored Pile to Friction Resistance of Unjani Clay

The small scale physical model of drum type was set-up to obtain the effect of water cement ratio (w/c) to pile capacity and original soil. The simulation of the process of providing bored piles model, soils model, installation and tests (pile loading tests and direct shear tests) under different water cement ratio of mortar and various moisture content of clay were done. The results reveal that the higher water content of original clay the bigger friction resistance, α value as clay soil is softer and the optimum w/c-ratio (w/c = 0,4) provides more pile capacity. It is understandable that water plays an important role, contributes to the change of surrounding clay properties. The improvement of Su ( % increase) due to compaction of concrete in bored pile, migration of moisture and reaction with surrounding clay leads to take benefit of design and construction of bored pile in clay soil for the sake of efficiency and stability.

Application of Ensemble Learning Using Weight Voting Protocol in the Prediction of Pile Bearing Capacity

Accurate prediction of pile bearing capacity is an important part of foundation engineering. Notably, the determination of pile bearing capacity through an in situ load test is costly and time-consuming. Therefore, this study focused on developing a machine learning algorithm, namely, Ensemble Learning (EL), using weight voting protocol of three base machine learning algorithms, gradient boosting (GB), random forest (RF), and classic linear regression (LR), to predict the bearing capacity of the pile. Data includes 108 pile load tests under different conditions used for model training and testing. Performance evaluation indicators such as R-square (R2), root mean square error (RMSE), and MAE (mean absolute error) were used to evaluate the performance of models showing the efficiency of predicting pile bearing capacity with outstanding performance compared to other models. The results also showed that the EL model with a weight combination of w 1 = 0.482, w 2 = 0.338, and w 3 = 0.18 corresponding to the models GB, RF, and LR gave the best performance and achieved the best balance on all data sets. In addition, the global sensitivity analysis technique was used to detect the most important input features in determining the bearing capacity of the pile. This study provides an effective tool to predict pile load capacity with expert performance.

Pile load tests at the deepest foundation piles in Germany

Since 2001 the so called Hafencity arises in Hamburg, Germany. Currently it is europes biggest urban development project. So far the most famous building of this area is the well known Elbphilharmonie. Now another impressive building is in planning – a huge skyscraper. The new skyscraper will get an over all height of 245 m. Due to the little bearing capacity of the ground a deep foundation is needed. To found the building Germanys deepest foundation piles, with length up to 75 m, will be executed. In advance, to determine the bearing capacity of the surrounding soil, four testpiles, with lengths up to more than 110 m, have been executed.